1. Field of the Invention
This disclosure is related to the field of devices for repairing asphalt deterioration. Specifically, this disclosure is related to raking tools utilized in the asphalt infrared repair process for the repair of potholes, raveled areas, utility cuts, and alligator cracks, amongst other instances of asphalt concrete degradation.
2. Description of Related Art
Asphalt concrete plays a huge role in the infrastructure of modern day westernized society. From its presence in roads, parking lots, driveways, airport landing strips and taxiways, asphalt pavement is an integral component in transit infrastructure.
Generally, in the art of asphalt paving, a road, parking lot, driveway or airport landing strip will be paved with an asphalt concrete with certain performance characteristics in terms of surface durability, tire wear, breaking efficiency, and roadway noise for the particular road and the type and degree of traffic the road is expected to bear. However, over time environmental factors and traffic loads can cause asphalt concrete to deteriorate. Often, both environmental factors and traffic loads contribute to asphalt deterioration and degradation. Environmental factors which cause deterioration include heat and cold, the presence of water in the subbase or subgrade soil underlying the pavement, and frost heaves, among other environmental factors. Traffic damage generally results from trucks and buses, and the damage caused is generally proportional to axle load raised by a certain degree. The deterioration and degradation caused by these factors includes, but is not limited to, crocodile cracking, potholes, upheaval, raveling, rutting, shoving, stripping and grade depressions, amongst others.
Irrespective of the causing agent, deterioration in asphalt roadways, parking lots and other surfaces is a major problem. The deterioration can cause damage to cars and vehicles, decrease transit efficiency, and create an unsightly roadway and parking lot infrastructure, among other problems. To avoid these problems, roadways, parking lots and other asphalt surfaces are regularly maintained to prevent and repair the degradation and deterioration of the asphalt surface that occurs over time.
One method commonly used in the art of asphalt paving to repair damage and degradation is known as infrared repair. The infrared repair process is capable of repairing potholes, raveled areas, utility cuts, alligator cracks, bumps and low spots, and drainage problems, along with many of the other deterioration problems commonly associated with asphalt pavement. The infrared process is generally preferred in the art of asphalt repair due to its low cost and ability to create a seamless repair by thermally bonding the edges of the repair area with the existing asphalt.
The infrared process generally takes place as follows. First, an infrared panel is placed over the area of the asphalt surface to be prepared. The panel is maintained over the repair area until the asphalt reaches a workable hot mix temperature, generally around 280°-300° F. The time required to reach this temperature will vary depending on the ambient temperature of the air and the asphalt pavement. The infrared rays which are utilized are desirable for their ability to heat the asphalt pavement without causing burning or oxidation. Once the repair area is heated to the desired working temperature, the repair area is raked to agitate the top of the asphalt as deep as they can, generally 1″ to 1.5″ of the asphalt, to scarify (i.e., make cuts or scratches in) the remaining asphalt, and to add new surface asphalt to the repair area. After the addition of the new surface asphalt to the repair area, the material is blended together and luted for proper elevation. After the blending and luting, the repair area is compacted with a compacting tool known to those of ordinary skill in the art such as a vibratory compactor, which compacts the edges of the repair area to the existing asphalt surface, thus creating a thermal bond with the existing pavement and eliminating any seams. To complete the process, the area is allowed to cool before it receives any traffic.
Notably, a seamless repair is possible through the infrared process because the entirety of the heated repair area becomes workable again. Stated differently, the heated asphalt and asphaltic cement that holds the rocks together becomes workable again. The new asphalt that is added to the heated area is generally highly concentrated in asphalt cement (the glue that binds the rock particles together) so that it can be redistributed throughout the repair area. When the repair area is compacted, the repaired area is thermally bonded or glued to the older portion of the asphalt pavement, creating a patch that is flush with the original asphalt pavement. Further, this process is significantly better for the environment than simply tearing out the section and replacing it as less new asphalt is needed, and there is less transportation cost for getting the asphalt to and from the worksite.
While the infrared repair process has many benefits over the other processes known to those of ordinary skill in the art for repairing asphalt, including its ability to create a seamless repair, the process as it is currently practiced in the art is latent with inefficiencies generally surrounding the manual raking process. For example, as noted previously, in the infrared process of the prior art once the repair area reaches a desired temperature after the application of infrared heat, the repair area is raked manually by a laborer. An example of an asphalt rake that is commonly used for this process is provided in Prior Art FIG. 1. Thus, in this step of the traditional infrared repair process, a laborer is required to stand over or around the heated asphalt patch and physically rake and move the hot asphalt to remove the top layer and agitate or scarify the remaining hot asphalt in the repair area. Inherently, this process is both labor intensive and time consuming. Often, the laborer must make multiple raked passes to sufficiently agitate and scarify the asphalt. In addition, after the agitation, a laborer needs to physically shovel the new heated asphalt mix into a wheelbarrow, transport it to the repair area, and rake and distribute it into the repair area. Both of these processes are physically exhaustive and extremely labor intensive due to the heat, fumes and the exertion needed to perform both jobs. The problems can be further exacerbated by certain types of asphalt repairs. For example, the infra-red heating can often not penetrate a boundary between two different asphalt lays, for example, as occurs in resurfacing. Thus, it can be necessary to agitate the entirety of the first level, and then work through that already agitated material, or completely remove it, to agitate the second.
Because these processes are labor-intensive jobs that require a great amount of physical strength and stamina, as a day progresses laborers often become fatigued and the quality, depth, and efficiency of their raking becomes compromised. Further, manual raking of the repair area by a laborer with an asphalt rake can be ineffective. Laborers can only apply a finite amount of down pressure on a hand rake. In addition, this pressure can vary across different points in the job and at different points in the day as a laborer becomes more fatigued. This varying amount of pressure applied to the rake generally results in portions of the repair area that are not raked to a required depth, resulting in the reemerging of cracks that will shorten the life of the repair. Generally, deeper raking is desirable and creates a better repair because it results in the removal of additional deep set cracks prior to the time the new asphalt mixture is introduced into the repair area. Thus, deeper raking generally results in a superior repair that will last longer.
Another limitation beyond a given laborer's varying strength throughout the day is the strength of the rake. It is not uncommon for an application of too much downward pressure on the rake to result in the rake breaking, which not only could temporarily comprise the repair but could also be potentially harmful to the worker. Moreover, in the traditional labor intensive infrared process, if a cold spot is encountered in the repair area it cannot be raked. Rather, the patch must be reheated, which requires more time and fuel, or the cold spot can simply be ignored, which often results in an inadequate repair.
Accordingly, there is a need in the art of asphalt repair for a device that will eliminate the inefficiencies and variability in quality inherent to the manual raking components of the infrared repair process.